add postgres exporter

Signed-off-by: Tuan-Dat Tran <tuan-dat.tran@tudattr.dev>

roles/postgres_exporter/handlers/main.yml

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+---
+- name: "Restart {{ bin_name }}"
+  ansible.builtin.service:
+    name: "{{ bin_name }}"
+    state: restarted
+  become: true

roles/postgres_exporter/tasks/get_version.yml

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+---
+- name: Determine latest GitHub release (local)
+  delegate_to: localhost
+  ansible.builtin.uri:
+    url: "https://api.github.com/repos/{{ repository }}/releases/{{ version }}"
+    body_format: json
+  register: _github_release
+  until: _github_release.status == 200
+  retries: 3
+
+- name: Set version
+  ansible.builtin.set_fact:
+    tag: "{{ _github_release.json.tag_name
+      | regex_replace('^v?([0-9\\.]+)$', '\\1') }}"
+
+- name: Set download_url
+  ansible.builtin.set_fact:
+    download_url: "https://github.com/{{ repository }}/releases/download/v{{ tag }}/{{ bin_name }}-{{ tag }}.linux-{{ go_arch }}.tar.gz"

roles/postgres_exporter/tasks/install.yml

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+---
+- name: Download/Extract "{{ download_url }}"
+  ansible.builtin.unarchive:
+    src: "{{ download_url }}"
+    dest: /tmp/
+    remote_src: true
+    mode: "755"
+
+- name: "Move binary into path: {{ bin_path }}"
+  ansible.builtin.copy:
+    src: "/tmp/{{ bin_name }}-{{ tag }}.linux-{{ go_arch }}/{{ bin_name }}"
+    dest: "{{ bin_path }}"
+    mode: "755"
+    remote_src: true
+  become: true
+
+- name: "Create user: {{ bin_name }}"
+  ansible.builtin.user:
+    name: "{{ bin_name }}"
+    shell: /sbin/nologin
+    state: present
+  become: true
+
+- name: Copy the node_exporter systemd unit file.
+  ansible.builtin.template:
+    src: "{{ bin_name }}.service.j2"
+    dest: "/etc/systemd/system/{{ bin_name }}.service"
+    mode: "644"
+  become: true

roles/postgres_exporter/tasks/main.yml

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+---
+- name: Get Version
+  ansible.builtin.include_tasks: get_version.yml
+- name: Install exporter
+  ansible.builtin.include_tasks: install.yml
+- name: Create service
+  ansible.builtin.include_tasks: systemd.yml

roles/postgres_exporter/tasks/systemd.yml

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+---
+- name: "Ensure service is running and enabled: {{ bin_name }}"
+  ansible.builtin.service:
+    name: "{{ bin_name }}"
+    state: started
+    daemon_reload: true
+    enabled: true
+  notify:
+    - Restart "{{ bin_name }}"
+  become: true

roles/postgres_exporter/templates/postgres_exporter.service.j2

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+[Unit]
+Description=PostgresExporter
+
+[Service]
+TimeoutStartSec=0
+User={{ bin_name }}
+ExecStart={{ bin_path }} --web.listen-address={{ host.ip }}:{{ bind_port }} {{ options }}
+Environment="DATA_SOURCE_URI=localhost:5432/postgres?sslmode=disable"
+Environment="DATA_SOURCE_USER={{ db.user }}"
+Environment="DATA_SOURCE_PASS={{ db.password }}"
+
+[Install]
+WantedBy=multi-user.target
+

roles/postgres_exporter/vars/main.yml

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+go_arch_map:
+  i386: "386"
+  x86_64: "amd64"
+  aarch64: "arm64"
+  armv7l: "armv7"
+  armv6l: "armv6"
+
+go_arch: "{{ go_arch_map[ansible_architecture] | default(ansible_architecture) }}"
+
+repository: "prometheus-community/postgres_exporter"
+bind_port: 9187
+version: "latest"
+serve: "localhost"
+options: ""
+bin_name: postgres_exporter
+bin_path: "/usr/local/bin/{{ bin_name }}"